Method and apparatus for suppressing the transfer of mechanical oscillations

ABSTRACT

THE TRAMSMITTAL OF MECHANICAL OSCILLATIONS OR IMPULSES IS SUPPRESSED ACCORDING TO THE INVENTION BY THE COOPERATION OF SPRING MEMBERS HAVING DIFFERENT SPRING RATES, WITH TRANSLATIONAL GEAR OR DRIVE MEANS HAVING TRANSLATION OR REDUCTION RATIOS WHICH ARE VARIABLE IN RESPONSE TO THE AMPLITUDE AND-OR SLOPE OF THE CHARACTERISTIC OF SAID OSCILLATIONS OR IMPULSES WHEREBY AN EXCURSION OF A POINT OF A FIRST DRIVE MEANS IS TRANSFERRED TO A SECOND DRIVE MEANS AT A PREDETERMINED, PREFERABLY AT A REDUCING RATIO, SAID SPRING MEMBER FOR THE FIRST DRIVE MEANS BEING SOFTER THAN THE SPRING MEMBER OF THE SECOND DRIVE MEANS.

Sept. 20, 1971 F. SCHAUMANN 3,606,298

METHOD AND APPARATUS FOR SUPPRESSING THE TRANSFER OF MECHANICAL OSCILLATIONS Filed Jan. 13, 1969 3 Sheets-Sheet l Fig.1

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METHOD AND APPARATUS FOR SUPPRESSING THE TRANSFER OF MECHANICAL OSCILLATIONS Filed Jan. 13, 1969 v 3 Sheets-Sheet 3 United States Patent METHOD AND APPARATUS FOR SUPPRESS- ING THE TRANSFER OF MECHANICAL OSCILLATIONS Fritz Schaumann, 28 Ringstrasse, (D 52) Siegburg, Germany Filed Jan. 13, 1969, Ser. No. 790,639 Claims priority, application Germany, Jan. 18, 1968, P 16 75 019.9 Int. Cl. F16f /00 U.S. Cl. 267-137 13 Claims ABSTRACT OF THE DISCLOSURE The transmittal of mechanical oscillations or impulses is suppressed according to the invention by the cooperation of spring members having different spring rates, with translational gear or drive means having translation or reduction ratios which are variable in response to the amplitude and/or slope of the characteristic of said oscillations or impulses whereby an excursion of a point of a first drive means is transferred to a second drive means at a predetermined, preferably at a reducing ratio, said spring member for the first drive means being softer than the spring member of the second drive means.

The present invention relates to a method and apparatus for suppressing the transfer of mechanical oscillations or impulses from a source to a mass. More specifically, the invention relates to spring suspensions for vehicle wheels comprising at least two spring members having different spring rates, which cooperate with translational drive means.

Spring suspension systems comprising two springs arranged in series and having different spring rates are known in the art. In one known arrangement a low friction spring is connected to a spring having an internal friction in order to achieve that smaller impacts are softly absorbed by the instantaneous reaction of the low friction spring so that such impacts are not transferred to the mass which is to be cushioned. However, in the prior art it was not possible to eliminate or at least suppress with equal effect small as Well as large impacts.

In view of the foregoing it is an object of the invention to suppress effectively the transfer of mechanical impacts from a source to a mass over a wide range of oscillation or impulse amplitudes.

Yet another object of the invention is to assure the the suppression of the transfer of oscillations and/ or impulses regardless of the nature or waveform of such oscillations or impulses. Stated differently, the suppression must be effective even if the oscillations or impulses have steep leading and/or trailing edges in their waveforms.

Thus, it is the main object of the invention to improve the suppression of the transfer of undesirable or disturbing oscillations or impulses to a mass, which transfer, prior to this invention, could not effectively be eliminated or at least suppressed.

It is yet another object of the invention to provide a I method and apparatus which, although especially useful for spring suspending vehicle wheels, is universally applicable for suppressing the transfer of mechanical oscillations or impulses from a source to a mass, for example, where a machine part is to be spring suspended.

A still further object of the invention is to provide means for the suppression of the transfer of oscillations or impulses from a source to a mass, which means may be arranged in series as well as in parallel with each other.

A still further object of the invention is to employ for the suppression of the transfer of oscillations and/or impulses, spring members having different spring rates, in combination with translational drive means of the lever or any other type, for example pinion and rack drive means, pneumatic drive means, and hydraulic drive means or any combination thereof.

According to the method of the invention, the forces which are effective between a mass and a source of oscillations or impulses are transferred to spring members through translational gear or drive means in such a manner that the translation ratio or the reduction ratio of at least one gear or drive means is variable in response to the amplitude and/or the slope of the waveform of the oscillation or impulse the transfer of which is to be suppressed.

In a preferred embodiment of an apparatus according to the invention, the impulse or oscillation source, for example, a wheel to be spring cushioned, is effective upon a first'relatively soft spring member through a first translational gear or drive means in such a manner that an excursion of a point upon which the oscillation or irnpulse becomes elfective, is transferred to a second gear or drive means at a reduction ratio, said second gear on drive means being effective upon a second spring member which is harder. than said first mentioned relatively soft spring member, and wherein the spring rates of the two spring members are selected in accordance with the translation ratios of the gear or drive means. For example, the spring rates may be proportional to the translation ratio of the gear or drive means.

According to a further feature of the invention there is provided an operational connection between the mass and a reference point on the first gear or drive means.

In another preferred embodiment of the invention the gears or drive means are positively interconnected with each other so that the ratio of the excursions of the spring members is independent of any variations in the load and/or the shape of the spring characteristics.

It is an advantage of the invention that at least one of the translational gears or drive means may be provided in the form of lever gear train or lever drive means because such lever means may be manufactured at relatively low costs.

A preferred embodiment of the invention comprises a double arm lever. The points upon which the impulse or oscillation source and the first spring member become effective, are arranged at opposite ends of the double arm lever. An operational connection to the mass is journaled to the lever approximately at its center and one or more connections to one or more further drive means is/are effective upon other points along said lever.

In order that the invention may be clearly understood it will now be described, by way of example, with reference to the accompanying drawings, wherein:

FIG. 1 shows an embodiment of the invention employing lever drive means in combination with two spring members and the drive means forming a parallel arrangement;

FIG. 2 illustrates schematically another embodiment which constitutes a further development of the embodiment of FIG. 1 with the drive gears arranged in parallel; and

FIG. 3 shows in principle an embodiment of the invention comprising three gear trains which cooperate with three corresponding spring members, said gear trains comprising gear wheels and toothed racks.

The gist of the invention will now be elucidated with reference to the embodiment shown in FIG. 1. A mass M to be cushioned is supported by spring means. The impulses which are to be dampened or the effect of which on the mass M is to be suppressed, are designated by the letter P at the point where the impulses become effective. The pulses P act upon one end 1a of a lever 1. The other end 1b of the lever 1 is connected to one end of a spring member F1. The lever 1 is pivotally connected at its pivot point to a plate 2. The plate 2 has an arm 2a which is attached to the other end of spring F1. The plate 2 is also connected to one end 3a of a lever 3 of a further lever drive means. The lever 3 is connected to the mass M by means of link or journal member 30. A spring member F2 is operatively connected to the other end 3b of the lever 3. The spring member F2 is further attached to the mass M.

The spring F1 is dimensioned so as to be relatively soft as compared to spring F2. On the other hand, a motion of the lever end 1a caused by an impulse P is transformed or translated into an increased deflection of the lever end 1b.

However, the translation of the lever 1 is not determined solely by the point Is. Rather such translation is variable in a sense, since for a given mass M the excursion of the s ring member F1 depends upon the amplitude and the slope of the impulse characteristic Which is to be suppressed with regard to its transmittal to the mass M, and because the spring excursion itself influences the translation ratio by vertically displacing the reference point 1d of the first lever drive means.

The same considerations apply in a corresponding sense to the reference point 3b of the second lever drive ns.

An operational connection R between the reference point 1d of the first lever drive means and the mass M keeps in equilibrium any tensional forces caused in the spring members F1 and F2, by impulses elfective on point 1a and which tensional forces exceed the forces required for supporting the mass M. Such equilibrium prevents an acceleration of the mass M if the spring rates of the spring members F1 and F2 are selected in such a manner that they correspond to the forces and excursions or translations transmitted by the lever system, and if the operational connection R is supported in the reference point 1d of the first translational gear drive means.

In the embodiment of a system as described above, the mass M may be accelerated only by impulses which are effective on point 1a whereby the motion of point 1d is reduced. The reduction ratio varies on the one hand with the square of the speed of motion of point 1a, and on the other hand in response to the instantaneous counter move of the spring members.

However, if the purpose of a particular use requires it, different effects or results may be achieved by dimensioning the spring members in a manner differing from that described above, and/or by supporting the operational connection R in a point other than the reference point 1d of the first translational gear drive means. For example, it is possible to obtain a slow acceleration of the mass M by means of spring forces exceeding the impulse forces so that the spring forces are not held in equilibrium anymore.

In the embodiments shown, the mass M is shiftable only in the vertical direction. However, the teaching of the invention may just as well be employed where the mass must be shifted, for example, horizontally or in any other direction.

Although FIG. 1 illustrates an embodiment with lever gear drives, it is also possible to employ other mechanical or hydraulical as well as pneumatic drive means. Thus, in the embodiment of FIG. 3 the drive means comprise gear wheels 10, 30, and 50 which COOperate with toothed racks 11, 12, or 31, 32, or 51, 52, said gear wheels and racks forming drive gears G1, G2, and G3. These drive gears cooperate with respective spring members F1, F2, and F3 which are shown, for example, as helical or spiral springs 13, 33 and 53.

The impulse P becomes effective against a base plate 14 of the drive gear G1. The drive gear G1 is positively connected in a force transmitting manner to a base p ate 34 through the rod 16 attached to the axle of the 4 gear wheel 10 and to said base plate 34 which forms the base plate for the next following drive gear G2. The spring member F2 or rather the helix or spiral spring 33 of the drive gear G2 is harder than the spring member F1 or rather the helix or spiral spring 13 of the drive gear G1.

Each of the shown drive gears G1, G2, and G3 constitutes for the corresponding spring member a translational gear with a gear ratio of 1:2. Of course, the number of drive gears may be selected as desired in accordance with any particular requirements.

Between the mass M and the reference point of the drive gear G1, that is between the mass M and the toothed rack 12 there is provided a fixed operational connection R which maintains, in the manner described with reference to FIG. 1, any excess tensional forces of the spring members F1, F2, and F3 in equilibrium. Thus, this operational connection R prevents any independent relaxation of the spring members.

In the embodiment of FIG. 3 it is quite possible to replace the gear wheels and toothed racks by hydraulic translational drive gears. Besides, the manner of operation is basically the same as that described with reference to FIG. 1.

Instead of a series arrangement of the drive means as shown in FIG. 3, it is also possible to employ a parallel arrangement. Such a parallel arrangement will now be described with reference to FIG. 2 which, for the sake of clarity, is shown in a schematic manner. The embodiment of FIG. 2 employes basically a lever drive arrange ment as shown in FIG. 1. Therefore, the same reference symbols as in FIG. 1 are employed in FIG. 2 for the same elements. However, as compared to FIG. 1, the embodiment of FIG. 2 comprises an additional lever 4 one end 4a of which is connected through a rod S to a point 12 on lever 1. The other end of lever 4 constitutes a fixed journal point 4b which is attached to the mass M. A point 40 on lever 4 is pivotally attached or hinged to point 3b of lever 3 and thus to the spring member F2 by means of a hinged connection member 5. The levers 1, 3 and 4 are dimensioned with regard to their length or with regard to the distances al to a4 and 121 to b4 between adjacent hinging or journal points provided on the levers, in such a manner that upon movement of the point In, the points 3b and 4c are displaced in parallel so that they may be provided with a common supporting Examples of the ratios of said distances al to a4 to the distances 121 to [24 may be given as follows:

The spring rate CF1 of the spring member F1 may, for example, have a ratio to that of the spring rate CFZ of the spring member F2 as follows:

CF2-48Z The lever 4 influences the total effect of the embodiment of FIG. 2 in the sense that it assures a constant ratio of the spring excursions or deflections of the spring members F1 and F2 even if the spring characteristics differ from each other or if, due to other influences a distortion of the spring deflection ratio would result but for lever 4. A change in the spring deflection ratio would influence substantially the horizontal or level position of the mass M. The invention avoids this and thus constitutes a substantial advance in the art.

While the invention has been described with reference to specific examples, it is to be understood that the invention includes all modifications and equivalents within the scope of the appended claims.

What I claim is:

1. An apparatus for suppressing the transfer of mechanical oscillations or impulses having given waveform characteristics including given amplitudes, from a source to a mass having an inertia, comprising translation means effectively interposed between said source and said mass, said translation means comprising at least two spring members having different spring rates, as well as drive means having a translational reduction ratio which is variable by said inertia in response to said Waveform characteristics, said spring rates being selected so that their ratio is proportional to said reduction ratio whereby the spring forces are maintained substantially in equilibrium independently of any instantaneous load condition exerted by said source through the drive means, and means for interconnecting the drive means and the spring members with the mass and the source for compensating any forces and moments exerted by said source, by the forces and moments exerted by said spring members so that the resultant forces and moments relative to said mass are substantially zero.

2. The apparatus according to claim 1, comprising a plurality of spring members having dilferent spring rates, and a plurality of translational drive means arranged between said spring members and said source for transmitting the oscillations or impulses to the spring members in such a manner that an excursion of a point of one of said dive means to which point said oscillations or impulses are applied, is transmitted to a further drive means at said reduction ratio, said further drive means cooperating with a spring member which is harder than a softer spring member with which said one drive means cooperates.

3. The apparatus according to claim 2, further comprising an operational connecting means connected to said mass and to a reference point on said one translational drive means.

4. The apparatus according to claim 2, further comprising connecting members arranged between said translational drive means for positively connecting the translational drive means with each other so that the ratio of the excursion of said spring members is independent of the shape of the spring characteristic of said spring members.

5. The apparatus according to claim 2, further comprising connecting members arranged between said translational drive means for positively connecting the translational drive means with each other so that the ratio of the excursions of said spring members is independent of any force applied to the spring members and independent of the shape of the spring characteristic of said spring members.

6. The apparatus according to claim 1, wherein at least one of said translational drive means is a lever drive arrangement.

7. The apparatus according to claim 1, wherein said translational reduction ratio of at least one of said drive means is variable in response to the amplitude of said oscillations or impulses.

8. The apparatus according to claim 1, wherein said translational reduction ratio of at least one of said drive means is variable in response to the slope of the waveform of said oscillations or impulses.

9. The apparatus according to claim 1, wherein said translational reduction ratio of at least one of said drive means is variable in response to the amplitude and the slope of the wavefrom of said impulses or oscillations.

10. An apparatus for suppressing the transfer of mechanical oscillations or impulses from a source to a mass comprising a plurality of spring members having different spring rates and a plurality of translational drive means arranged between said spring members and said source for transmitting the oscillations or impulses to the spring members in such a manner that an excursion of a point of one of said drive means to which point said oscillations or impulses are applied, is transmitted to a further drive means at a reduction ratio, said further drive means cooperating with a spring member which is harder than a softer spring member with which said one drive means cooperates, wherein at least one of said translational drive means is a lever drive arrangement comprising in a first lever drive including a double arm lever having two 0pposite arms, an outer end of one arm being adapted for cooperation with said source, the outer end of the opposite lever arm being adapted for cooperation with a first one of said spring members, and an operational connecting member attached at one end of its ends to said mass while the other end is journaled to said double arm lever approximately intermediate its ends, and further comprising additional drive means cooperating with respective ones of said spring members and further connecting members arranged between said additional drive means and journaled to said double arm lever at other points therealong.

11. An apparatus for suppressing the transfer of mechanical oscillations or impulses from a source to a mass comprising a plurality of spring members having different spring rates and a plurality of translational drive means arranged between said spring members and said source for transmitting the oscillations or impulses to the spring members in such a maner that an excursion or a point of One of said drive means to which point said oscillations or impulses are applied, is transmitted to a further drive means at a reduction ratio, said further drive means cooperating with a spring member which is harder than a softer spring member with which said one drive means cooperates, wherein at least one of said translational drive means comprises a pinion, a journal member for said pinion, and two toothed racks cooperating with said pinion, a support for one of said racks, and means for supporting the other rack by one of said spring members.

12. The apparatus according to claim 11, wherein a plurality of said translational drive means are connected in series with each other in that the pinion journal member of a first drive means is rigidly attached to the rack support member of the next drive means, and wherein the pinion support member of the last drive means of a series is connected to said mass.

13. The apparatus according to claim 11, comprising an operational connection between the spring support rack and the mass for guiding said spring support rack.

References Cited UNITED STATES PATENTS 3,121,373 2/1964 Murphy et a1. 267--1 (71) 3,441,238 4/1969 Flannelly 267l(78) JAMES B. MARBERT, Primary Examiner US. Cl. X.R. 267--l80 

